The proposed research is a longitudinal and sequential follow-up study of a group of patients with prior acute coronary heart attacks. The overall goal is to develop and validate a method which will prospectively identify and characterize those individuals who die suddenly (abruptly or within 24 hours after symptom onset) from a repeat acute coronary heart attack. Prospective data to be collected include details of the severity and type of coronary heart attack. Prospective data to be collected include details of the severity and type of coronary heart attack at entrance into the study and triannual follow-up information of six-hour taped ambulatory cardiac rhythm recordings, interim symptoms and affect state. These variables will be related to a variety of clearly defined endpoints including the severity of repeat coronary heart attacks, sudden cardiac death and severity of follow-up cardiac arrhythmias. Data processing techniques will be utilized for data handling, storage and retrieval and data analysis which involves both Chi squared tabular relationships and step-wise discriminant analysis techniques. BIBLIOGRAPHIC REFERENCES: Moss A.J.: Therapeutic uses of permanent permanent pervenous atrial pacemakers: A review. J. Electrocard. 8:373, 1975. Moss A.J.: Profile of high risk in people knwon to have coronary heart disease: A review. Circulation III 51 and 52-147, 1975.